Систематизация математических зависимостей для оценки вентиляционных потерь мощности в осевой турбинной ступени, в цилиндре, в паровой турбине

Abstract

In the world practice of steam turbine construction, dozens of different, usually empirical mathematical dependencies (formulas) have been used to calculate ventilation power losses in the axial turbine stage. The formulas cover a wide range of parameters that affect the amount of ventilation losses. There is a significant error in calculations relative to experimental data for specific types of turbines. The comparative analysis of the known formulas allowed us to group the dependencies properly and identify the boundaries of their appropriate application, to establish those of them, the calculations for which lead to minimal errors relative to the experimental data, as well as to identify a formula that can be used to determine ventilation heating. The interest in ventilation modes of operation of TPP steam turbines is caused by the need to increase the efficiency of equipment due to the increasing cost of organic fuel and further expansion of combined generation of electricity and heat, related to solving the problem of converting powerful heating turbines to three-stage heating of network water, searching for rational operation of the Central heating system during periods of failures of electric load schedules and implementing specific operating modes, such as motor mode, the need to ensure high maneuverability of the equipment of power units, TPP, power units in whole. At the same time, the problem of ensuring the systematic deepest discharge of the TPP during the night failure of the electrical load schedule [1-3]; increasing the number of cases of forced operation of the condensing unit with increased pressure, described in [4, 5], is put forward as a number of priorities. Reducing heat losses in the condenser and increasing the share of electricity generated by heat consumption is the main direction of improving the efficiency of heating turbines. The solution of these problems is mainly related to the organization of the most economical operation modes of steam turbines Central heating system. In the operation modes of start-stop, idle, emergency load relief, heating, motor, hot rotating reserve, the characteristics of the turbine spade device are entirely determined by the influence of ventilation phenomena that occur and flow in the flow part of the cylinder (ventilation power losses) [3], ventilation heats [6], intense excitation of bending-torsional axial resonant vibrations by a screw flow of working steam pulsating with a frequency of, equal to the speed of rotation of the ventilation flow in the gap between the diaphragm and the grid of the working blades in the range of 0.560-0.572 of the shaft speed, due to the regular impact of uneven rotating ventilation flow by alternately stretching and compressing the passage section of the working steam flow, and can lead to failure of the working blades [7].